Quick Links

ontheweb WWW.FINEHOMEBUILDING.COM FREE VIDEO: Measure accurate angles with scraps of paper In this recent episode of There’s a Better Way, Chuck Miller shows how to make perfect miter cuts without a protractor or an angle gauge. Find hundreds more tips, techniques, and tool reviews in Fine Homebuilding’s free online video series: • There’s a Better Way • Building Skills • Tool Hound breaktime Advice from our website If you haven’t visited the blogs on FineHome building.com, then you’re missing out on a fascinating exchange of ideas, advice, and commentary. Also visit “Breaktime,” our online discussion group, to ask a question. It’s free to sign up. Chimney leak MONTANAMAN EXPLAINS: After a 2-in. snowfall, I noticed one wet brick in the center of my chimney about halfway up on the inside. The chimney runs up the outside of the house. There are two flues, and there is a cathedral ceiling. FREE eLetter Want Fine Homebuilding delivered every week? Sign up for our free eLetters at FineHomebuilding.com/eLetter. Raising the bar on energy efficiency Want to learn more about the details and materials that make the town houses on pp. 56-63 superefficient? FineHomebuilding.com’s sister site GreenBuildingAdvisor.com has a collection of the most comprehensive design and how-to resources for building or renovating a house to Passive House standards. Visit GreenBuilding Advisor.com/passive-house. Is this likely a flashing leak where the chimney enters the roof, or a leak in the concrete chimney cap? Any words of wisdom would be appreciated. DanH replies: Two in. of snow amounts to maybe ¼ in. of water—not very much. It’s likely that snow pooled up at the joint between the chimney and the roof. It’s also possible that the leak is in the cap and that water is leaking down the outside of the flue liners but inside the chimney brick. Calvin adds: If the leak is between the two flues and the surrounding brick, it could be the cap or a gap between the flue and crown. A concrete cap should have a space between it and the flue liner packed with a nonflammable “rope,” then caulked to just above the top of the crown. Constant fluctuations in temperature can erode the concrete next to the flue; that’s why a cap needs the gap, backer, and caulk. Of course, the leak could be at the chimney flashing, or perhaps the siding-to-brick joint if the chimney runs up the outside of the house. I hope there’s no black roof goop up there. That would almost guarantee later failure and complicate finding the real source of the problem. If water comes down the inside of the flue, there may be a crack or space in the flue that allows water to get between it and the brick. It finds a place to collect and appears in the middle of nowhere. This is not good and potentially is unsafe. Exhaust gases (smoke) and small burning embers floating up the flue might find their way to a place where you don’t want them to end up. Photos: top, John Ross; bottom, Rob Yagid.